BOSTON (AP) — East Coast businesses are bracing for a possible walkout of 14,500 workers that could close 14 ports from Massachusetts to Texas.

The latest talks between shipping companies and dockworkers broke down Tuesday, less than two weeks before the contract expires Dec. 29. That's led to worries a strike is inevitable.

The National Retail Federation wrote to President Barack Obama this week to ask him to use "all means necessary" to head off a strike, which it fears could have catastrophic economic ripple effects.

A key sticking point is royalty payments union workers get, based on the weight of cargo received at each port. The container carriers and port operators want to cap the payments, saying they're too large and hurting competitiveness.

The union says they're an important supplemental wage and fund critical benefits.